"TOKYO — On the evening of March 12, the Fukushima Daiichi nuclear plant’s oldest reactor had suffered a hydrogen explosion and risked a complete meltdown. Prime Minister Naoto Kan asked aides to weigh the risks of injecting seawater into the reactor to cool it down.

At this crucial moment, it became clear that a prime minister who had built his career on suspicion of the collusive ties between Japan’s industry and bureaucracy was acting nearly in the dark. He had received a confusing risk analysis from the chief nuclear regulator, a fervently pro-nuclear academic whom aides said Mr. Kan did not trust. He was also wary of the company that operated the plant, given its history of trying to cover up troubles."